The long term objective is to understand the structure, replication, and mechanisms of inheritance of the ribosomal genes. Toward this end we are studying the structure of DNA in chromosomes and how the ribosomal genes might differ in structure from the rest of the DNA. A combination of genetic and biochemical approaches are envisioned. Techniques to be used include sucrose gradient sedimentation, gel electrophoresis, nucleic acid hybridization, fluorescence, and specific enzyme digestion.